代码： 文字滚动，简版

.offset()返回的是相对于document的位置

.position()返回的是相对于父元素的位置

文字滚动（文字滚屏）小效果：

<script type="text/javascript" src="http://cdn.bootcss.com/jquery/1.11.2/jquery.min.js"></script>
<style type="text/css">
#demo{position:relative;width:120px;height:200px;border:1px solid #ececec;font-size:16px;line-height:20px;font-family:'微软雅黑';overflow:hidden;}
#demo11{position:absolute;width:6em;}
</style>
<br><br><br>
<div id="demo">
    <div id="demo11">
    1366****1111
    1366****1111
    1366****1111
    1366****2222
    1366****2222
    1366****2222
    1362****6666
    1362****6666
    1362****6666
    1366****7777
    1366****7777
    1366****7777
    1368****8888
    1368****8888
    1368****8888
    </div>
</div>
<script>
$(function(){
    function mar(){
        //var H = $("#demo11").height()- $("#demo").height() +20;
        var H = $("#demo11").height();
        var top = $("#demo11").position().top;
        top--;
        if(top<(-1*H)){top=$("#demo").height();}
        $("#demo11").css('top',top);
        console.log('H:'+H+'---top:'+top+'---'+$("#demo11").position().top);
    }
    var timer=setInterval(mar,50);
    $("#demo").mouseover(function(){
        clearInterval(timer);
    });
    $("#demo").mouseout(function(){
        timer=setInterval(mar,50);
    });
});
</script>

 改写成对象型：

<script type="text/javascript" src="http://cdn.bootcss.com/jquery/1.11.2/jquery.min.js"></script>
<style type="text/css">
#demo{position:relative;width:120px;height:200px;border:1px solid #ececec;font-size:16px;line-height:20px;font-family:'微软雅黑';overflow:hidden;}
#demo11{position:absolute;width:6em;}
</style>
<br><br><br>
<div id="demo">
    <div id="demo11">
    1366****1111
    1366****1111
    1366****1111
    1366****2222
    1366****2222
    1366****2222
    1362****6666
    1362****6666
    1362****6666
    1366****7777
    1366****7777
    1366****7777
    1368****8888
    1368****8888
    1368****8888
    </div>
</div>
<script>
$(function(){
var txtMarquee = {
    timer:null,
    _box:null,
    _boxH:null,
    _txt:null,
    _txtH:null,

    init:function(_box,_txt){
        txtMarquee._box = _box;
        txtMarquee._txt = _txt;
        txtMarquee._boxH = _box.height();
        txtMarquee._txtH = _txt.height();
        //txtMarquee._txtH = _txt.height() - _box.height() + 20;

        txtMarquee.timer=setInterval(txtMarquee.mar,50);
        _box.mouseover(function(){
            clearInterval(txtMarquee.timer);
        });
        _box.mouseout(function(){
            txtMarquee.timer=setInterval(txtMarquee.mar,50);
        });
    },
    mar:function(){
        var top = txtMarquee._txt.position().top;
        top--;
        if(top<(-1*txtMarquee._txtH)){top = txtMarquee._boxH;}
        txtMarquee._txt.css('top',top);
        //console.log('H:'+txtMarquee._txtH+',   top:'+top+'   ,  '+$("#demo11").position().top);
    }
}
txtMarquee.init($("#demo"),$("#demo11"));
});
</script>

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